One way a zone has been isolated in the past is to put a fracture opening between spaced seals and deliver pressure between them. The seals are typically packers and the outlet between them is typically the only one provided in a straddle assembly. These assemblies are typically run on coiled tubing. There are several disadvantages of such an arrangement. One is that there is no access to the borehole below when the packers above and below are set and the only outlet is between them. Another disadvantage is that if the lower packer refuses to release there is only limited access to the lower packer for dislodging debris by a release of the upper packer. Even when doing this there is limited space for the debris to go past the upper unset packer and the frac port, if used for circulation is well above the lower packer.
Ported sleeves in general are discussed in US 2014/0014340; US 2015/0129218; US2015/0129197; U.S. Pat. No. 7,661,478; U.S. Pat. No. 8,844,634; and U.S. Pat. No. 7,926,574.
The present invention offers a simple design that opens a frac port with compression against a lower set packer which is then followed with setting the upper packer for interval fracturing between the packers. Releasing the upper packer and then pulling tension closes the upper port and opens a through passage in the housing that has an exit either above or below the bottom packer. An exit above the lower packer allows a circulation jetting action right above the lower packer to clean away debris that has built up from the fracturing that could make the lower packer harder to release. A through housing outlet below the lower packer allows treatment below the straddle tool or operation of some other tool located further downhole. The frac port is also contoured to minimize erosion effects of the exiting fracturing fluid and its entrained solids. These and other aspects of the present invention will be more readily apparent to those skilled in the art from a review of the description of the preferred embodiment and the associated drawings while recognizing that the full scope of the invention is to be found in the appended claims.